Dear Sir. Concerning your issue about the homogeneity and Stability testing for reference material. I think the following below links may help you in your analysis:

https://file.scirp.org/pdf/Detection_2013071914212086.pdf

http://edepot.wur.nl/198205

http://www.microbiologics.com/core/media/media.nl?id=39644&c=915960&h=53dcd8715fefe4e6f412&_xt=.pdf

Thanks

Thank you Isam Eldin Hussein Elgailani , the article recommended is very useful for preparation of microbiological reference material. I think more details on some aspects will be clarified by the references quoted.

Hello, do not forget about ISO 17034:2016 and ISO Guide 35:2017

Regards !